I have two Excel sheets: One which tracks Campaign Responses (CRs) and one which tracks Leads. I've created a relationship link between the shared Date field which has allowed me to put all of the metrics on one table, which is great. What I want to do now is create a filter which works for both CRs and Leads. Using the shared "Geo" field as an example, I followed the steps outlined here: http://onlinehelp.tableau.com/v10.0/pro/desktop/en-us/help.htm#filter_across_datasources.html but the filter I created only filters the primary "Lead" data, and not the CR data as well. Any ideas on how to get the filtering working across both datasets?

Go to the CR (Book 1) data source in the Data Window and click the little chain link icon so that it turns orange. This will allow you to use it as a "linking field" and the filter will work how you intended.

For future reference, the filtering across data sources feature is intended more for if you have multiple sheets (often on one dashboard) that come from different data sources and you want one filter to be applied to all of them. In this case, since you only have one sheet, you actually don't need to take advantage of this feature. This example is just an application of data blending.

I have one other question for you. On my real dataset, some of the CR data is missing (For example, on around ~10% of CRs there is no record for Geo so it's left blank). When I link the fields, it lowers the total amount of CRs displayed on my table. Is there any way I can have the full amount of CRs displayed, and then when a Geo is selected have it filter from there?